DA0-002 Data Analysis Practice Test 8 — 15 Questions

Question 1

A data analyst is testing whether the average sales amount differs between two regions. Which statistical test is most appropriate?

Accepted Answer

Two-sample t-test. A two-sample t-test compares the means of two independent groups.

Answer

Chi-square test

Answer

ANOVA

Answer

Paired t-test

Question 2

In time series decomposition, a pattern that repeats at regular intervals (e.g., weekly, yearly) is called:

Accepted Answer

Seasonality. Seasonality refers to regular, periodic patterns in time series data.

Answer

Cyclical

Answer

Irregular

Answer

Trend

Question 3

Which data quality dimension is most concerned with whether data values fall within a defined domain or acceptable range?

Accepted Answer

Validity. Validity refers to whether data values conform to defined rules or constraints.

Answer

Completeness

Answer

Consistency

Answer

Accuracy

Question 4

A data analyst is examining the relationship between advertising spend (in dollars) and revenue (in dollars). The Pearson correlation coefficient r is calculated as +0.92. Which of the following interpretations is correct?

Accepted Answer

There is a strong positive linear relationship.. r = +0.92 indicates a strong positive linear relationship.

Answer

There is a strong negative linear relationship.

Answer

There is no linear relationship.

Answer

92% of the variation in revenue is explained by advertising spend.

Question 5

A data analyst is cleaning a dataset and finds that a numeric field has several missing values. The variable is normally distributed. Which imputation method is most appropriate?

Accepted Answer

Mean imputation. For normally distributed data, mean imputation is common and preserves the mean.

Answer

Median imputation

Answer

Mode imputation

Answer

Forward-fill

Question 6

In a multiple regression model with three predictors, the coefficient for one predictor is 5.2 with a p-value of 0.001. Which of the following is the best interpretation?

Accepted Answer

The predictor has a statistically significant effect on the dependent variable, controlling for other variables.. The coefficient indicates the change in the dependent variable for a one-unit increase in the predictor, holding other predictors constant.

Answer

The predictor explains 5.2% of the variance in the dependent variable.

Answer

A one-unit increase in the predictor decreases the dependent variable by 5.2 units, on average.

Answer

The model is not a good fit because one predictor is significant.

Question 7

A data analyst wants to compare the means of three different training methods on employee productivity. Which statistical test is most appropriate?

Accepted Answer

ANOVA. ANOVA (Analysis of Variance) is used to compare means of three or more groups.

Answer

Correlation analysis

Answer

Chi-square test

Answer

t-test

Question 8

A data analyst is preparing a dataset for analysis and needs to handle outliers. Which TWO of the following are common methods for treating outliers?

Accepted Answer

Removal. Capping (winsorizing) limits extreme values, and removal simply deletes outlier rows. Transformation (e.g., log) can also reduce impact but is not listed here; normalization and imputation are not primary outlier treatments.

Answer

Normalization

Answer

Imputation

Answer

Standardization

Question 9

An analyst is conducting an A/B test on a new checkout process. To calculate sample size, which THREE factors must be considered?

Accepted Answer

Desired effect size. Statistical power, significance level (alpha), and desired effect size (minimum detectable effect) are essential for sample size calculation.

Answer

Number of control groups

Answer

Population standard deviation

Question 10

A data analyst is building a logistic regression model to predict whether a customer will churn (yes/no). Which TWO statements about logistic regression are correct?

Accepted Answer

The output is a probability between 0 and 1.. Logistic regression outputs probabilities between 0 and 1, and can use a sigmoid function. It is a classification algorithm, and coefficients represent log-odds changes.

Answer

It is used only for time series forecasting.

Answer

The dependent variable is continuous.

Answer

It requires normally distributed errors.

Question 11

A data analyst is examining sales data for a retail chain and notices that the mean monthly sales is $50,000 while the median is $35,000. Which of the following best describes the distribution of the sales data?

Accepted Answer

The distribution is right-skewed.. When the mean is greater than the median, the distribution is right-skewed (positively skewed) because the mean is pulled towards the higher values by outliers or a long right tail.

Answer

The distribution is bimodal.

Answer

The distribution is left-skewed.

Answer

The distribution is symmetrical.

Question 12

A data analyst is comparing the average test scores of students who attended a tutoring program versus those who did not. Which statistical test is most appropriate for determining if there is a significant difference between the means of these two independent groups?

Accepted Answer

Two-sample t-test. The independent samples t-test is used to compare the means of two independent groups.

Answer

Paired t-test

Answer

Chi-square test

Answer

ANOVA

Question 13

In a linear regression model predicting house prices, the coefficient for the number of bedrooms is $30,000 and the intercept is $50,000. If a house has 3 bedrooms, what is the predicted price?

Accepted Answer

$140,000. Using y = mx + b, predicted price = 30000 * 3 + 50000 = $140,000.

Answer

$80,000

Answer

$150,000

Answer

$90,000

Question 14

A data analyst wants to segment customers into groups based on their purchasing behavior. The dataset includes numerical features such as annual income and purchase frequency. Which algorithm is most appropriate for this task?

Accepted Answer

K-means clustering. K-means clustering is a common algorithm for customer segmentation based on numerical features.

Answer

Linear regression

Answer

Logistic regression

Answer

Chi-square test

Question 15

A data analyst is preparing data for a k-nearest neighbors algorithm. The features include age (0-100) and income (0-200,000). Which technique should be applied to ensure the distance metric is not dominated by income?

Accepted Answer

Min-max normalization. Min-max normalization scales features to a 0-1 range, ensuring each feature contributes equally to distance calculations.

Answer

Log transformation

Answer

Z-score standardization

Answer

One-hot encoding